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Andrew Wright
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Does electric perm and magnetic perm give you enough info to work out OD?
Thanks in advance
Thanks in advance
vanhees71 said:As far as I know "optical density" is an oldfashioned expression for the absorption coefficient, i.e., it's rather related to the imaginary part of the refractive index, the extinction coefficient
Andrew Wright said:Summary:: Hi. Is there a formula for getting OD from electric permativity and magnetic permeability?
Does electric perm and magnetic perm give you enough info to work out OD?
Thanks in advance
...there is not a single-valued ε or μ for the entire sample.
Andrew Wright said:Does this mean the perms have different values at different wavelengths?
When a substance is subject to static electric and magnetic fields, its polarization is proportional to the present (constant!) applied field.Andrew Wright said:I'll keep trying. I know light is an em wave but the concepts of perms predate the understanding of em waves. So how can the values vary with wavelengths if really it is about fields that don't need wavelengths?
Optical density is a measure of how much a material can block or absorb light. It is typically represented by the symbol "OD" and is used to describe the transparency or opacity of a substance.
Optical density is directly related to the permittivity and permeability of a material. Permittivity refers to a material's ability to store electric charge, while permeability refers to its ability to support the formation of magnetic fields. These properties affect how light passes through a material, and therefore impact its optical density.
Yes, optical density can be calculated from permittivity and permeability using the formula OD = 2 * ln(μ/ε), where μ is the permeability and ε is the permittivity. This formula is derived from the relationship between these properties and the refractive index of a material.
Optical density is a dimensionless quantity, meaning it has no units. It is typically represented as a decimal or a logarithmic value.
Optical density can be measured using a spectrophotometer, which measures the amount of light absorbed by a sample. The results are typically recorded as a numerical value, with higher numbers indicating a higher optical density and therefore less light passing through the sample.